Building with panels of dissimilar materials

ABSTRACT

A fastening system for attaching cladding panels to a carrier panel and allowing for differential thermal expansion. The system fastens the two panels together at points in the direction perpendicular to the panel planes. A combination of different carrier panel hole sizes and slots fix the panels together at one point and allow the panels to expand and contract relative to each other while maintaining rectangular alignment. Wall panels and buildings constructed using the fastener are disclosed.

BACKGROUND OF THE INVENTION Field of Invention This invention relates toa fastening system for attaching panels of one material to a panel of adissimilar material. CROSS-REFERENCE TO RELATED APPLICATIONS

Subject matter disclosed herein is disclosed in the following copendingapplications filed contemporaneously herewith and assigned to theassignee of the present invention:

Fastening System for Assembling Panels of Dissimilar Materials(CN-1003);

Wall Panels of Dissimilar Materials (CN-1101); and

Method for Assembling Panels of Dissimilar Materials (CN-1103).

BACKGROUND OF THE INVENTION

It is known to attach panels of dissimilar materials together by usingadhesive bonding, such as silicone adhesives. Adhesive bonding isproblematic in that typical adhesives have low static load strengths,leading to adhesive failure and separation of the panels. Typicaladhesives used in the building industry have a modulus of elasticitywhich allows unacceptable movement between panels. Simple mechanicalfasteners do not allow for movement due to differential expansion andcontraction between panels of dissimilar materials.

There is a need for a fastening system to fasten two panels ofdissimilar materials, e.g., aluminum and filled acrylic composite, insuch a way that differential growth of one panel relative to the otherdoes not cause warping of either panel. There is also a need for afastening system that can be assembled with access to only the backsideof one panel.

SUMMARY OF THE INVENTION

An embodiment of the invention is a fastening system for panels ofdissimilar materials, which comprises a threaded fastener, a captive nutwith a through hole which is formed from a flat body with a first face;a shoulder protruding from the first face; a polygonal extensionprotruding from the shoulder; and a captive washer comprising a washerbody; and a polygonal cutout sized to fit the said polygonal extension.

In another embodiment, slotted holes in a first panel allow both panelsto expand and contract relative to each other while maintainingrectangular alignment.

In another embodiment, a wall panel is constructed from the assembly ofan aesthetic panel and a carrier panel fastened together by thefastening system for panels of dissimilar materials.

In another embodiment, a building is constructed with wall panelsconstructed from the assembly of an aesthetic panel and a carrier panelfastened together by the fastening system for panels of dissimilarmaterials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of the fastening system.

FIG. 2A shows a wall panel assembled with the fastening system and twopanels of dissimilar materials.

FIG. 2B shows a wall panel assembled with the fastening system and twopanels of dissimilar materials employing an optional anchor.

FIG. 3A shows a carrier panel with through holes.

FIG. 3B shows a carrier panel with through holes and slots.

DETAILED DESCRIPTION

The present invention is not limited to fastening any specific type ofpanels to one another for any specific application. The fastening systemof the present invention may be used for panels of such materials aswood, stone, metal or plastic. It is found to be especially useful forfastening panels of an aesthetic material to a support panel for use asbuilding cladding. For purposes of illustration, one panel will becalled an aesthetic panel (600), and the other will be called a carrierpanel (700).

Panel Fastening System

The panel fastening system (500) is comprised of three components, acaptive nut (100), a captive washer (200), and a threaded fastener(300). The components may be made of metal, or some other suitablystrong and durable material, using standard manufacturing methods.Preferred materials are aluminum or an engineering plastic.

Captive Nut

The captive nut (100) comprises four integral components, a main body(105), a shoulder (110), an extension (120), and a through hole (130).In a preferred embodiment, the captive nut will be a unitary membermachined from one piece of material, wherein each component will extendout from one side of the main body (105), i.e., the shoulder willcommence at the face of the main body and extend therefrom, and thepolygonal extension will commence at the shoulder and extend therefrom.However, the captive nut components may be manufactured individually andthen assembled to form the captive nut as shown in FIG. 1. The fourcomponents share a centerline (400).

The main body (105) may be formed in any shape that allows an installerto hold it in a manner to prevent rotation during installation. Ingeneral, the main body will be a flat shape that can be grasped by ahandtool, such as a pliers or wrench. FIG. 1 illustrates the main bodyof the captive nut with an outer surface in the shape of a hexagon,which is the preferred shape. The hexagon shape allows the captive nutto be held with a conventional wrench. The other integral components ofthe captive nut will not rotate when the main body is held captive.

The shoulder (110) on the captive nut establishes a controlled-dimensiongap between the captive nut and captive washer (200) when they areassembled to fasten to a carrier panel (700). The gap dimension isselected to be a slip fit for the carrier panel held between the captivenut and captive washer. The shoulder extends from a face of the mainbody.

The polygonal extension (120) is a polygonal shape that extends from theshoulder (110). It is sized to fit into the cutout (230) in the captivewasher (200), to be discussed below. The extension may be of anypolygonal shape that will not rotate inside of a correspondingly shapedhole. The polygon may be formed from straight sides, curvilinear sides,or a combination thereof. When the extension of the captive nut is matedwith the cutout of the captive washer both the captive washer and thecaptive nut are prevented from rotation when the main body is heldcaptured by a wrench. This allows the fastening system to be assembledwith access to only the backside of the carrier panel (700). Forpurposes of illustration, a hexagon shaped extension and cutout areused.

A through hole (130) commences on a face of the captive nut oppositethat from which the shoulder and polygonal extension extend, and runsthrough the entirety of the combined main body, shoulder, and polygonalextension. The through hole provides a means for a threaded fastener(300) to pass through the captive nut and fasten to a panel (600).

Captive Washer A captive washer (200) comprises a washer body (210), anda polygonal cutout (230). A function of the captive washer, along withthe captive nut, is to form a gap that is a slip fit for a carrier panel(700) held between the captive nut and captive washer. The captivewasher also establishes a space between the two panels, which lowersfriction between them and allows free movement due to differentialexpansion and contraction.

A purpose of the washer body (210) is to distribute the pressure of thethreaded fastener (300) evenly over the carrier panel (700), reducingthe chance of damage thereto. The shape of the washer body is notcritical. A generally annular shape is preferred.

The cutout (230) is a polygonal-shaped through hole in the washer body.The shape and size is a sliding fit for the extension (120). It iscritical that the cutout matches the extension and be of a geometry thatprevents the extension from rotating inside the cutout.

Optionally, a resilient washer (220) that serves as a spring while thethreaded fastener (300) is being tightened may be employed. Anyresilient washer, such as, split washers, Bellville washers, wavywasher, and star washers may be used. Preferably, a foam washer may beused between the face of the washer body (210) and the panel (600). In apreferred embodiment, the foam washer is adhesively bonded to the washerbody (210) for ease of installation.

Threaded Fastener

Any threaded fastener (300) suitable for the panel (600) into which thethreaded fastener will be driven may be used. In embodiments where thepanel does not readily accept a threaded fastener, an anchor (302) maybe used. An example of suitable anchors are those supplied by FischerFastening Systems of Auburn Hills, Mich., and the undercut anchorssupplied by KEIL Befestigungstechnik GmbH of Engelskirchen, Germany.

Optional Slots in Carrier Panel

The present invention requires through holes (710) in the carrier panelto allow the threaded fastener to penetrate through the carrier panelinto the aesthetic panel. There is no limitation on the size, shape, ornumber of through holes used. It is found useful to use a combination ofcircular holes and oblong slots to allow controlled movement between thedissimilar panels while maintaining rectangular alignment. Asillustrated in FIG. 3, through holes of different sizes, and slots maybe included in carrier panel (700) at locations where threaded fastenerswill pass through the carrier panel. At one point a reference hole (710)is sized to fit close around the outer diameter of a captive nutshoulder (110). This point connection becomes a fixed connection pointbetween the panels.

Panel slots (720, 730, 740 a) are used at the corners of the carrierpanel. The panel slots are elongated in the direction coincident withthe slot's position from the reference hole. Consequently, as theaesthetic panel expands or contracts relative to the carrier panel theslots will allow unconstrained linear movement between the dissimilarpanels. Optionally, a larger diameter hole (740 b) may be used at thecorner diametrically opposite the reference hole. The combination ofthrough holes and panel slots allow the panels to move relative to eachother while maintaining alignment.

Fastening System Installation

The present invention is not limited to fastening any specific type ofpanels to one another for any specific application. For purposes ofillustrating the installation of the fastening system, a first panelknown as an aesthetic panel (600), will be fastened to a second panelknown as a carrier panel (700). Through holes (710) are provided in thecarrier panel to allow the threaded fastener (300) to fasten theaesthetic panel to the carrier panel.

As a first step in installing the fastening system, provision is madefor the threaded fastener (300) to thread into the aesthetic panel(600). The threaded fastener may be driven directly into the aestheticpanel in situations where the material of the aesthetic panel readilyaccepts screw threads. In situations where the material of the aestheticpanel may crack, a blind pilot hole may be drilled into the back surface(600 b) of the aesthetic panel. When simple threaded fasteners areeither impractical or ineffective, a screw anchor (302) may be used. Thescrew anchor is installed into the back surface of the aesthetic panel(600 b) according to the manufacturer's instructions and specifications.Threaded fasteners should not penetrate through the front surface of theaesthetic panel (600 a) so as to maintain the aesthetic appeal of thepanel.

The captive washer (200) is positioned on the aesthetic panel with thecutout (230) aligned with the point on the carrier panel where thethreaded fastener (300) will be driven. The carrier panel (700) ispositioned opposite the aesthetic panel in a position where a throughhole in the carrier panel (710) is aligned with the captive washer. Acaptive nut (100) is inserted into the through hole in a manner whichmates the polygonal extension (120) and the cutout (230). The threadedfastener (300) is inserted through the through hole (130) in the captivenut (100). A wrench is placed on the main body (105) to prevent thefastening system from spinning and the threaded fastener is driven intothe aesthetic panel.

Application in Building Construction

The present invention is not limited to fastening any one specific typeof panel to any other type of panel, for any specific application. Thefastening system of the present invention may be used for anycombination of panels of such materials as wood, stone, metal orplastic. For purposes of illustration it is found to be especiallyuseful for fastening a first panel of an aesthetic material to a second,supporting, carrier panel for use as building cladding. The carrierpanel is typically a structural metal wall panel. An example of astructural metal wall panel is the Dri-design Wall Panel System fromDri-Design of Holland, Mich. Two or more holes are drilled into astructural metal wall panel that are utilized as the carrier panel(700). A threaded fastener (300) is fit through a captive nut (100), andthen through a hole in the carrier panel. A captive washer is placed onthe threaded fastener on the opposite side of the carrier panel andassembled to the captive nut by mating the extension (120) on thecaptive nut to the cutout (230) on the captive washer. The threadedfastener is then driven into the aesthetic panel to fasten the carrierpanel to the aesthetic panel to form a wall panel. It is found useful toprevent the captive nut and captive washer from spinning while thethreaded fastener is driven into the aesthetic panel by holding the mainbody (105) with a wrench.

It is found that an aesthetic panel of solid surface material will givea pleasing appearance and good weathering characteristics. Corian® solidsurface from DuPont of Wilmington, Del. is an example of an acceptablesolid surface material.

Numerous wall panels, formed from aesthetic panels fastened to carrierpanels, are assembled to the exterior structure of a building to createwalls.

The following examples further illustrate the invention.

EXAMPLE

An aesthetic panel made of Corian® solid surface material was placed ona workbench surface with the finished side face-down on the worksurface. The Corian® panel had previously had undercut holes for Keilanchors machined into the back face. Consequently, these undercut holeswere exposed on the backside of the Corian® panel. Keil anchors wereinserted in each of the undercut holes.

Captive washers were positioned on each Keil anchor with the cutout inthe captive washers capturing the extension of the Keil anchor. Thecaptive washers were positioned so the resilient washer adhered to oneface of the captive washers was between the captive washers and thebackside of the Corian® panel. The resilient washer was made of foam.

A mating Dri-Design aluminum carrier panel was then placed on top of thecaptive washers, with the holes and slots in the carrier panel alignedwith the through holes in the captive washers.

A captive nut was then inserted through the single small diameterreference hole in the carrier panel with the captive nut extensioninserted into the cutout in the captive washer. The position of thecarrier panel was then slightly adjusted so the shoulder featurediameter of the captive nut was aligned with the carrier panel holediameter so the captive nut shoulder was inserted into the panel holeand the shoulder face came into contact with the surface of the captivewashers.

Captive nuts were then inserted through the carrier panel slots withcaptive nut extensions inserted into the cutouts in the captive washers.The position of the carrier panel was slightly rotated around thecaptive nut previously placed in the small diameter reference hole sothe shoulder feature diameter of the captive nuts were aligned with theDri-Design panel slot edges so the captive nut shoulders were insertedinto the panel slots and the shoulder faces came into contact with thesurface of the captive washers. Captive nuts were similarly inserted andaligned in all the slots along the two perpendicular axes of slots tocomplete the alignment of the two dissimilar panels

Captive nuts were then inserted through the remaining large diametercarrier panel hole, with captive nut extensions inserted into thecutouts in the captive washers.

Bolts with a proper length to span the distance between the Keil anchorsand the back face of the carrier panel were then dropped into thethrough holes of each captive nut. Each bolt was then threaded into themating Keil anchor and tightened to the proper torque value, whileholding the main body of the captive nut with a wrench.

What is claimed is:
 1. A building comprised of wall panels constructedfrom the assembly of an aesthetic panel and a carrier panel fastenedtogether by a fastening system for panels of dissimilar materials, thefastening system comprising: (a) a threaded fastener: (b) a captive nutwith a through hole comprising: (i) a main body with a first flat face;(ii) a shoulder protruding from the first flat face; (iii) a polygonalextension protruding from the shoulder; (c) a captive washer comprising;(i) a washer body; and (ii) a polygonal cutout sized to fit the saidpolygonal extension.